1. Field of the Invention
The present invention relates to an automobile bumper beam which is made of fiber-reinforced resin and configured to be disposed in a vehicle width direction.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2014-24394 has made known a rear bumper beam made of fiber-reinforced resin and formed by stacking two layers of a continuous fiber-reinforced resin layer and a discontinuous fiber-reinforced resin layer, and provided with two vertically arranged U-shaped sectional portions each opened toward a rear side of a vehicle body, in which opening actions of the U-shaped sectional portions attributed to a collision load are controlled by blocking openings at outer ends in a vehicle width direction of the U-shaped sectional portions by using an end wall.
In addition, U.S. Pat. No. 7,954,865 has made known a bumper beam provided with a honeycomb structure body fixed to an end portion in the vehicle width direction of the bumper beam by using hooks, in which an impact load obliquely inputted to the end portion in the vehicle width direction of the bumper beam is absorbed by a crush of the honeycomb structure body.
Meanwhile, a planar shape of the above-described conventional rear bumper beam is curved in an arc shape such that a central part in the vehicle width direction projects rearward with respect to outer end portions in the vehicle width direction which are attached to rear ends of a pair of right and left rear side frames. Accordingly, an impact load in case of a rear end collision is inputted as a load concentrated on a single point to the central part in the vehicle width direction of the rear bumper beam. Thus, an extremely large bending moment acts on the central part in the vehicle width direction of the rear bumper beam which is located away from attaching portions to the rear side frames. As a consequence, the rear bumper beam may be locally fractured at that part and may fail to sufficiently exert its energy absorption performance. In order to avoid this situation, a plate thickness of the rear bumper beam may be increased to improve its bending strength. However, this measure leads to a problem of an increase in weight of the rear bumper beam. Moreover, there is another problem that it is difficult to obtain a sufficient energy absorption performance by blocking the openings at the outer ends in the vehicle width direction of the U-shaped sectional portions only by using the end wall, when an impact load is obliquely inputted to the end portion in the vehicle width direction of the bumper beam.
On the other hand, according to the bumper beam described in U.S. Pat. No. 7,954,865, the honeycomb structure body is fixed to the bumper beam by using the hooks. For this reason, the honeycomb structure body may fall off the bumper beam due to the obliquely inputted impact load and may fail to sufficiently exert its energy absorption performance.